The present invention relates to a method for operating a refrigeration device with a refrigerating circuit with two evaporators arranged in parallel to each other which cool thermally-separated refrigerator compartments which can have different compartment temperatures, as well as a compressor, with which the two evaporators are able to have coolant applied to them separately. The present invention also relates to such a refrigeration device for executing the inventive method of operation.
A fridge-freezer combination is known from DE 199 57 719 A1 in which the refrigerator compartment and the freezer compartment are cooled by evaporators arranged in a parallel circuit to each other and supplied by one and the same compressor. A magnetic valve allows the refrigerator compartment evaporator and the freezer compartment evaporator to have coolant applied separately to them, which makes separate temperature regulation of the two compartments possible.
A problem associated with having parallel circuits for the refrigerator compartment evaporator and for the freezer compartment evaporator is that during the idle time of the compressor, as a result of the different temperatures of the two evaporators, coolant evaporated in the refrigerator compartment has a tendency to flow into the freezer compartment and to condense there. If subsequently as a result of a demand for cooling of the refrigerator compartment the compressor is switched on and coolant is pumped around through the refrigerator compartment evaporator, the amount of coolant available is small and the cooling power able to be obtained is low, so that long compressor operating times or in extreme cases even malfunctions can occur.
To alleviate this problem, it is proposed in DE 199 57 719 A1 that a section of the freezer compartment evaporator in which coolant collects during the idling period of the compressor be designed so that this section, in respect of a coolant filling volume, is designed to be filled at least approximately with its entire volume of liquid coolant in the idle phase of the compressor, and to place it so that, if the compressor is switched on as a result of a cooling request from the refrigerator compartment, the coolant flowing through the coolant circuit of the controlled refrigerator compartment evaporator flows with the liquid coolant from the stated section of the freezer compartment evaporator, which causes the latter to cross into the coolant circuit of the controlled refrigerator compartment evaporator. The disadvantage however is that the carry-over effect is weaker, the smaller the mass flow rate through the refrigerator compartment evaporator is. I.e. the more liquid coolant has collected in the freezer compartment evaporator, the smaller is the rate at which it is extracted from the freezer compartment evaporator and can be fed back to the flow of coolant through the refrigerator compartment evaporator. This likewise results in increased compressor run times and thus in an increased energy use of the refrigeration device. A complete solution to the problem has thus not yet been achieved.